In the past, much effort has been devoted to the development of fall prevention devices known as rope grips. The desirable qualities of such a device fall into several catagories, including, safety, reliability, versatility, and convenience of use.
Dodge Machine Co., Inc. currently offers a rope grip with a number of desirable qualities, for example the rope grip is manufactured from large simple pieces of material which distribute the impact of a fall through relatively massive pieces of metal providing for strength, reliability, and safety. It can be attached to a person by means of a lanyard so that it can be moved up and down the rope without the person having to place his hand on the grip, which makes the rope grip convenient to use. This rope grip can be placed over a rope anywhere along the length of a rope, providing for further convenience. This rope grip is versatile, it can be used with ropes having a variation in diameter of as much as a quarter of an inch.
Another commercially available rope grip is the Barrow Hepburn Everest Rope Grip, patented in the U.K. with U.K. Pat. No. 1,077,068. This rope grip operates by means of three small steel balls through which the rope is passed. When the grip begins to fall rapidly down a rope, the friction of the rope against the balls draws them into a conical shaped housing which jams the rope between the three balls. While this device offers advantages over many others in terms of fail-safe operation, it too has practical drawbacks. This device can only be used with a very narrow tolerance in rope diameter. The device lacks versatility. The rope must be threaded through the rope grip as it cannot be opened for placing the grip on the rope, nor can it be opened for cleaning. It is not possible to move this grip past a splice or a knot on the rope. Thus, this rope grip is in many ways inconvenient to use. A safety device such as this one, which is inconvenient to use does not provide maximum effectiveness since it is likely that a person engaged in an activity where a rope grip should be used will not use a device which interferes with the activity, as this rope grip can.
The available rope grips, such as those noted above, provide varying degrees of fail-safe operation. This feature however, is gained at the expense of versatility and convenience. In accordance with the present invention, these and other disadvantages of the prior art are minimized. The present invention provides a high degree of fail-safe operation while remaining versatile and convenient to use.